1. Field of the Invention
The invention relates to a vehicle steering device including right and left steering operation mechanisms configured to respectively turn right and left steered wheels, in which the right and left steering operation mechanisms are not mechanically coupled to a steering member that is operated for steering, and the right and left steering operation mechanisms are respectively driven by right and left steering motors.
2. Description of the Related Art
For purposes of implementing advanced driving support functions typified by autonomous driving and improving flexibility of engine compartment layouts, effectiveness of a steer-by-wire system that does not use an intermediate shaft has begun to be highly regarded. In order to further improve the flexibility of engine compartment layouts, as described in Japanese Patent Application Publication No. 2008-174160 (JP 2008-174160 A) and Japanese Patent Application Publication No. 2015-20586 (JP 2015-20586 A), right and left independent steering systems have been proposed in which steering gear devices including a rack-and-pinion mechanism are not used and right and left steered wheels are controlled by independent steering actuators.
In the steer-by-wire system, a steering motor is feedback controlled so that an actual steered angle is equal to a target steered angle. When the deviation between the actual steered angle and the target steered angle is equal to or larger than a predetermined value, it is determined that some type of abnormality has occurred, and failure processing is performed in general. By the failure processing, the steering motor is stopped, for example.